docs: def _compute_distance(self, rup, dists, imt, C):
          """
          Compute the second term of the equation described on p. 199:
  
          ``(b4 + b5 * M) * log(sqrt(Rjb ** 2 + b6 ** 2))``
          """
          return (((C['b4'] + C['b5'] * rup.mag)
                   * np.log10((np.sqrt(dists.rjb ** 2.0 + C['b6'] ** 2.0)))))